JPS6254676B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a recording head drive circuit of a thermal recording device that selectively applies current pulses to a large number of heating elements disposed on the recording head to form a desired pattern on thermal recording paper. It is to be closed.

In the above-mentioned thermal recording device, a large number of heat generating elements are divided into several groups (hereinafter referred to as blocks) due to the size of the drive circuit, the power supply capacity, and the thermal characteristics of the recording head. It is common to record one line in several parts.

In this case, the heating elements included in each block are driven simultaneously regardless of the recorded content, so
The capacity of the recording power supply was designed to accommodate an all-black screen, but the proportion of black that actually occupied the screen was very low and wasted a lot.

This tendency is particularly strong in high-speed thermal recording devices.
In order to improve this point, a circuit is configured so that the heat generating element group included in each block can be divided into several stages of driving, and the number of black spots in the recording dots corresponding to each block is changed. A driving method that changes the number of divisions has been proposed.

However, in this method, the division position within each block is fixed and is unrelated to the black distribution of recording dots, so even if the proportion of black is not that large, the number of divisions increases and the recording speed does not increase. The situation was ripe.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for driving a thermal recording head with a simple structure and signal processing, which can improve the drawbacks of the conventional method and achieve a higher recording speed with a smaller power supply capacity.

In order to achieve this object, the present invention provides a thermal recording head drive circuit which has a large number of heat generating elements disposed on the recording head and drives each heat generating element simultaneously with electricity according to recording data stored in a data register. , a plurality of switching means provided for each small group that further divides a group of simultaneously driven heat generating elements, and counting the number of "recorded" in the recorded data transferred to the data register for each small group. The first counting means also counts the number of "recorded" in the recorded data and generates a carry pulse every time the number reaches a predetermined value, and at the same time the count value of the first counting means is counted. a second counting means loaded;
third counting means for counting the carry pulses;
a fourth counting means for counting the number of times of the energization drive;
a comparing means for detecting coincidence of the count values of the third and fourth counting means; a register for sequentially storing the comparison results by the comparing means at the end of transfer of recording data corresponding to the small group of heating elements; means for selecting the switching means according to stored data, and for each of the heat generating element small groups whose number is in a range where the number of "recorded" does not exceed a predetermined value,
When the "recorded" count reaches a predetermined value, only the heat generating element small groups that have been completely counted are driven at the same time, and "recorded" for the heat generating element small groups that have not been completely counted. It is characterized in that it is added and counted during the next drive.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a schematic block diagram of a thermal recording apparatus according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a recording head, on one side of which a group of 720 heating elements 2 are arranged in one row. The lead wires separating each heating element are drawn out alternately on both sides and divided into lead wire groups 3 and 4. The lead group wires 3 pass through a diode group 5 and a matrix wiring section 7, and are grouped into 180 wires and connected to a switching circuit group 9 having 180 switching circuits (one block). On the other hand, the lead wire group 4 passes through the diode group 6 and the matrix wiring section 8, and is combined into 4×9 lead wires and connected to the switching circuit group 10. The switching circuit 9 operates according to the output of the data register 11 which stores 180 recording signals (for one block).
The 180 lead wires are selectively connected to the negative side of the recording power source 13. On the other hand, switching circuit group 1
0 selectively connects 4×9 lead wires to the plasma side of the recording power source 13 according to the output of the block selection section 12, and controls the number of small blocks to be actually energized.

By connecting 180 lead wires on the data register 11 side and a set of 9 lead wires on the block selection section 12 side to the recording power source 13, current flows through the 180 heat generating elements in the heat generating element group 2. Heat is generated, and the surface of the thermal recording paper that is in contact with this heating element develops color.

On the recording head 1, 180×4=720 heating elements are arranged in one row, and while the 180 pieces of recording data stored in the data register 11 are replaced, the four sets of lead wires on the block selection section 12 side are By sequentially connecting the recording power sources 13 to the recording power source 13, a one-line recording pattern can be obtained on the heat-sensitive recording paper.

While repeating the above-described one-line recording operation, a two-dimensional recording pattern is formed by intermittently feeding the thermosensitive recording paper in a direction perpendicular to the arrangement direction of the heating element group 2.

FIG. 2 is a block diagram showing the detailed configuration of the block selection section 12 in FIG. 1, and FIG. 3 is a signal waveform diagram for explaining the operation of the block selection section 12.

During the period when the strobe signal 101 is output, one block worth of recording signal 102 and transfer clock pulse 1 are output.
03 is the data register 11 and block selection section 12
180 pieces of recording data are stored in the data register 11 and applied to the switching circuit group 9. On the other hand, in the block selection section 12, at the end of the strobe signal 101, the energization pulse generation section 14 sends the energization pulse 106 to the logic gate section 15, and the result of the logical operation between the outputs of the block selection register 16 and the small block selection register 17 is processed. Therefore, the energizing pulse 106 is applied to a portion of the 9 x 4 signal lines input to the switching circuit group 10.

When the final (9th) small block is selected,
The energizing pulse 106 passes through the gate 18 and is sent out as a block recording end signal 104. If the final (fourth) block is selected at this point, the energizing pulse 106 passes through the gate 19 and is sent out as a line feed signal 105.

On the other hand, the dot counters 20 and 21 count the transfer clock pulses 103 only when the recording signal 102 indicates black, and count the number of black included in the recorded dots. The counter 22 has a transfer clock pulse of 10
It is a 20-decimal counter that counts 3, and generates a reset pulse 107 at the beginning of a transfer pulse group corresponding to each small block. Since the dot counter 21 is reset to the beginning of each small block by the reset pulse 107, it counts the number of blacks contained in each small block. The dot counter 20 is a 48-base counter, and generates a carry pulse 108 every time the number of blacks reaches 48, increments the count of the upper counter 23 by one, and simultaneously outputs the output of the dot counter 21 at that point. Load it into yourself.

The data comparator 24 generates a match signal 109 between the output of the counter 23 and the counter 25, and the presence or absence of the match signal 109 is written into the small block selection register 17 at each small block break by a reset pulse 107. Further, the counter 25 increments by one each time one recording data transfer is completed by the energizing pulse 106.

Therefore, the output of the small block selection register 17 simultaneously selects small blocks within a range where the sum of the numbers of black recorded dots does not exceed 48.

Each time the smallest small block is selected, gate 1
8 is opened, and at the trailing edge of the energizing pulse 106, the data in the block selection register 16 is shifted one by one, and each block is sequentially selected.

The recording data of the first block is transferred to the strobe signal 101, the recording signal 102, and the transfer clock pulse 1.
03, each time the energizing pulse 106 is sent out, the block recording end signal 104 is sent repeatedly.
Each time the line feed signal 105 is sent out, the recorded data is sequentially replaced with that of the next block, and each time the line feed signal 105 is sent out, the paper is fed by one line, and by repeating the above operations, the desired data is obtained. recording pattern is obtained.

As shown in Figure 3, one line is divided into four blocks (one block is 180 pixels), each block is divided into nine small blocks (one small block is 20 pixels), and the power supply generates heat in 48 pixels at the same time. This is an example of a case where the current capacity is sufficient to record black dots.

Next, the recording operation in FIG. 3 will be explained in more detail.

(1) Recording operation of the first block First recording operation 1 While the signal 101 is at a high level, one block of recording signals (180 pieces) of the first block is input from t1 to t12. This recording signal 101 is stored in the data register 11.

2. The dot counter 20 counts the number of black dots in the recording signal 102 and outputs a carry pulse 108 every 48 dots.

The dot counter 21 counts the number of black spots in the recording signal 102, but the reset pulses 107, t2, t3, t5, t6, t from the counter 22
7, t8, t10, t11, and t12, its contents are always the number of blacks in that small block.

The counter 22 counts the clock signals 103 and outputs a reset pulse 107 every 20 (one small block) to reset the dot counter 21 as described above.

3 Carry pulse 108 from dot counter 20
t1 to t4 are counter 2 until output.
Since the contents of bits 3 and 25 are both 0 and the output signal 109 of the data comparator 24 is at high level (coincidence), the small block selection register 17 stores the small block position of the reset pulse 107 generated during this time.

4 When the carry pulse 108 is output from the dot counter 20 at t4, the contents of the dot counter 21 are loaded into the dot counter 20, and the counter 23 becomes 1. As a result, the output signal 109 of the data comparator 24 becomes a low level (inconsistency), so that the small block position of the reset pulse 107 is no longer stored. As a result, the first and second recording positions are set as the first recording position.
The small block position is small block selection register 17
is memorized.

5. When the signal 101 falls at t12, the energizing pulse 106 is generated from the energizing pulse generator 14 in synchronization with this, and the first recording of the first block (first and second small blocks) is performed.
This energizing pulse 106 causes the counter 25 to become 1.

Second recording operation 1-2 Same as above 3 Carry pulse 108 from dot counter 20
From t21 to t24, the content of the counter 23 is 0, the content of the counter 25 is 1, and the output signal 109 of the data comparator 24 is at a low level (inconsistency). The small block position of the generated reset pulse 107 is not stored.

4 When the carry pulse 108 is output from the dot counter 20 at t24, the dot counter 20
Since the contents of the pupil dot counter 21 are loaded into the pupil dot counter 21, the contents of the dot counter 20 change to count the number of blacks from the beginning t3 of the third small block. At the same time, the counter 23 becomes 1 and the output signal 109 of the data comparator 24 becomes high level (match), so that the subsequent reset pulse 1
The small block position of 07 is now stored in the small block selection register 17. This state is t
This continues until the count value of the dot counter 20 reaches 48 at step 29 and the next carry pulse 108 is output. As a result, the third to sixth small block positions are stored in the small block selection register 17 as the second recording positions.

5 When the signal 101 falls at t22, the energizing pulse 106 is generated from the energizing pulse generator 14 in synchronization with this, and the second recording of the first block (3rd small block to 6th small block) is performed. . This energization pulse 106 causes the counter 25 to become 2.

Third recording operation 1-2 Same as above 3 Carry pulse 108 from dot counter 20
From t41 to t44, the content of the counter 23 is 0, the content of the counter 25 is 1, and the output signal 109 of the data comparator 24 is at a low level (inconsistency). The small block position of the generated reset pulse 107 is not stored.

4 When the carry pulse 108 is output from the dot counter 20 at t44, the dot counter 20
Since the contents of the dot counter 21 are loaded into the dot counter 21, the contents of the dot counter 20 change to count the number of blacks from the beginning t48 of the third small block. At the same time, the counter 23 becomes 1, but the counter 25 is 2, so the output signal 109 of the data comparator 24 remains at a low level (non-coincidence), so that the subsequent small block position of the reset pulse 107 is not stored. This state is t49
When the count value of the dot counter 20 reaches 48, the next carry pulse 108 is output and the count value of the dot counter 20 reaches 48.
This continues until 3.

5 When the carry pulse 108 is output from the dot counter 23 at t49, the dot counter 20
Since the contents of the dot counter 21 are loaded into the dot counter 21, the contents of the dot counter 20 change to count the number of blacks from the beginning t49 of the seventh small block. At the same time, the counter 23 becomes 2 and the output signal 109 of the data comparator 24 becomes high level (match), so that the subsequent reset pulse 1
The small block position of 07 is now stored in the small block selection register 17. This state is t
This continues until the signal falls at 52. As a result, the seventh to ninth small block positions are stored as the third recording positions.

6 When the signal 101 falls at t52, the energizing pulse 106 is generated from the energizing pulse generator 14 in synchronization with this, and the third recording of the first block (7th small block to 9th small block) is performed. .

7 When the ninth small block is selected, the gate 18 is opened, and the energizing pulse 106 is output as the block recording end signal 104, which increments the block selection register 16 and selects the next second small block.
Let's move on to the block record.

(2) Third block recording operation 1 The same recording operation as above is performed in two steps.

(3) Recording operation of the third block 1 A recording operation similar to the above is performed once.

(4) Recording operation 1 of the fourth block The same recording operation as above is performed in three steps.

2. The energizing pulse 106 applied to the ninth small block of the fourth block passes through gates 18 and 19 and becomes a line feed signal 105.

FIG. 4 is an explanatory diagram showing an example of divided recording,
(1) is a case where the ratio of black is low, (3) is a case where the proportion is almost completely black, and (2) is a case between (1) and (3). In FIG. 4, in order to make it easier to understand, the recording dots included in one block are arranged in the order of recording data transfer and the number is reduced, but in reality they are distributed discretely and there are many.

According to this embodiment, since recording is performed in such a way that the recording current is always kept close to a constant level according to the distribution of black on the recording screen, waste of power supply capacity is drastically reduced, and the recording speed is reduced. Recording can be performed using a small and inexpensive heat-sensitive recording device. Furthermore, since the amount of heat generated in the recording head is averaged, thermal design becomes easier and the recording characteristics are also favorably affected.
Furthermore, compared to conventional technology that simply changes the number of divisions in divided recording, the number of divisions can be increased without complicating the circuit or signal processing, making it possible to perform much more effective divided recording with a simple configuration. Can be done.

As described above, according to the present invention, thermal recording can be performed at a higher recording speed with a smaller power supply capacity, and the circuit configuration and signal processing thereof are simple.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of a recording section of a thermal recording apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing a detailed configuration of a block selection section in FIG. 1, and FIG. FIG. 2 is a waveform diagram for explaining the operation of the block selection section, and FIG. 4 is an explanatory diagram showing a divided recording method by a thermal recording apparatus according to an embodiment of the present invention. 1... Recording head, 2... Heat generating element group, 10...
...Switching circuit group, 11...Data register, 12...Block selection section, 15...Logic gate section, 17...Small block selection register, 20...
...Dot counter (second counting means), 21...
Dot counter (first counting means), 23... counter (third counting means), 24... data comparator, 25... counter (fourth counting means).

Claims (1)

[Claims] 1. In a thermal recording head drive circuit that has a large number of heat generating elements arranged on a recording head and simultaneously drives each heat generating element with electricity according to recording data stored in a data register, a group of heat generating elements that are driven simultaneously is further provided. a plurality of switching means provided for each divided small group; a first counting means for counting the number of "recorded" data in the recorded data transferred to the data register for each small group; a second counting means that counts the number of "recorded" in the data and generates a carry pulse every time the number reaches a predetermined value, and at the same time the count value of the first counting means is loaded; a third counting means for counting the carry pulse; a fourth counting means for counting the number of energization drives; a comparison means for detecting coincidence of the counts of the third and fourth counting means; A register for sequentially storing the comparison results by the comparing means at the end of transfer of recording data corresponding to a small group of elements, and means for selecting the switching means according to the data stored in this register are provided. For each heat generating element small group whose number does not exceed a predetermined value, and when the count of "recorded" reaches a predetermined value, only the heat generating element small groups that have been completely counted are simultaneously driven. A thermal recording head drive circuit characterized in that "recorded" small groups of heating elements that have not been completely counted are included and counted during the next drive.